A double-blind study evaluated the impact of imipramine on cognitive function in 61 patients with Alzheimer's disease. Twenty-eight patients had coexistent depression and dementia; 33 had dementia only. All were randomly assigned to an 8-week trial of imipramine or placebo. For both depressed and nondepressed subjects, the effect of imipramine on cognition was minimal. A subtle decrement in general cognitive function was evident in those treated with imipramine, as compared with those treated with placebo. No effects were observed on memory. Clinicians are advised that very low doses of imipramine (25 mg/daily) may be tolerated in depressed Alzheimer patients, but that cognitive changes do occur in some patients and should be carefully monitored.